Measurement of hydrated water in D-glucose powder using THz-wave spectroscopy

In this paper, we introduce a new method to measure the amount of water of crystallization in D-glucose powder using terahertz (THz) wave spectroscopy. We measured five crystalline D-glucose samples: one anhydrous, one monohydrate, and three in various states of partial dehydration, whose water content was measured independently by using Karl Fischer's method. By analyzing the THz absorption spectra, particularly the absorption peaks at 60.3, 65.6, and 80.5 cm ^-1, which are strongly correlated with the hydration ratio, we could obtain a highly reliable analytical curve, with a correlation coefficient of 0.9509 and a standard error of prediction of 0.714. This study suggests the possibility of measuring the water of crystallization nondestructively, without using an organic solvent.